Re: [libvirt] [RFC PATCH 3/9] vfio/pci: register a default migration region

On Wed, 4 Dec 2019 22:26:38 -0500 Yan Zhao <yan.y.zhao(a)intel.com&gt; wrote: > Vendor driver specifies when to support a migration region through cap > VFIO_PCI_DEVICE_CAP_MIGRATION in vfio_pci_mediate_ops->open(). > > If vfio-pci detects this cap, it creates a default migration region on > behalf of vendor driver with region len=0 and region->ops=null. > Vendor driver should override this region's len, flags, rw, mmap in > its vfio_pci_mediate_ops. > > This migration region definition is aligned to QEMU vfio migration code v8: > (https://lists.gnu.org/archive/html/qemu-devel/2019-08/msg05542.html) > > Cc: Kevin Tian <kevin.tian(a)intel.com&gt; > > Signed-off-by: Yan Zhao <yan.y.zhao(a)intel.com&gt; > --- > drivers/vfio/pci/vfio_pci.c | 15 ++++ > include/linux/vfio.h | 1 + > include/uapi/linux/vfio.h | 149 ++++++++++++++++++++++++++++++++++++ > 3 files changed, 165 insertions(+) > > diff --git a/drivers/vfio/pci/vfio_pci.c b/drivers/vfio/pci/vfio_pci.c > index f3730252ee82..059660328be2 100644 > --- a/drivers/vfio/pci/vfio_pci.c > +++ b/drivers/vfio/pci/vfio_pci.c > @@ -115,6 +115,18 @@ static inline bool vfio_pci_is_vga(struct pci_dev *pdev) > return (pdev->class >> 8) == PCI_CLASS_DISPLAY_VGA; > } > > +/** > + * init a region to hold migration ctl & data > + */ > +void init_migration_region(struct vfio_pci_device *vdev) > +{ > + vfio_pci_register_dev_region(vdev, VFIO_REGION_TYPE_MIGRATION, > + VFIO_REGION_SUBTYPE_MIGRATION, > + NULL, 0, > + VFIO_REGION_INFO_FLAG_READ | VFIO_REGION_INFO_FLAG_WRITE, > + NULL); > +} > + > static void vfio_pci_probe_mmaps(struct vfio_pci_device *vdev) > { > struct resource *res; > @@ -523,6 +535,9 @@ static int vfio_pci_open(void *device_data) > vdev->mediate_ops = mentry->ops; > vdev->mediate_handle = handle; > > + if (caps & VFIO_PCI_DEVICE_CAP_MIGRATION) > + init_migration_region(vdev); No. We're not going to add a cap flag for every region the mediation driver wants to add. The mediation driver should have the ability to add regions and irqs to the device itself. Thanks, Alex

> + > pr_info("vfio pci found mediate_ops %s, caps=%llx, handle=%x for %x:%x\n", > vdev->mediate_ops->name, caps, > handle, vdev->pdev->vendor,